This invention relates to electronic musical instruments, and more particularly relates to such instruments capable of providing an accompaniment in different harmonies selected by a performer.
Electronic musical instruments, such as keyboard-controlled electronic organs, have experienced wide acceptance among musicians. Since many of these instruments are sold to amateurs, manufacturers have placed special emphasis on featurs which promote ease of playing. In particular, the electronic musical instrument industry has long sought a method of producing an accompaniment in different harmonies which can be selected easily by a performer of limited skill or musical knowledge.
Attempts in this direction have been made in the past. For example, U.S. Application Ser. No. 3,584, entitled "Orchestral Accompaniment Techniques", filed Jan. 15, 1979 in the names of R. J. Hall, G. R. Hall and J. C. Cookerly and assigned to the same assignee as this application, describes a major advance in generating and controlling a musical accompaniment by an electronic musical instrument. This application is incorporated by reference.
The instrument includes a tempo clock which divides each musical measure into beats and each beat into 12 subparts. The instrument plays an accompaniment depending on the harmony selected by the performer by depressing keys on a standard keyboard. In order to minimize the skill required by the performer, the instrument recognizes only the harmony selected at the beginning of a musical beat. As a result, the performer can lift his hand from the keyboard and begin selecting another harmony as soon as the beat has commenced. The accompaniment continues for the duration of the beat in the selected harmony even though the performer's hand is no longer depressing any keys.
Experience has shown that the foregoing arrangement creates difficulties for the performer who is so unskilled that his selection of harmony is not completed until after a beat has commenced. If no harmony (or an improper harmony) is selected at the beginning of a beat, the lack of harmony (or improper harmony) will continue through the entire beat even though the performer selects the proper harmony a fraction of a second after the beat commences.
Thus, it is one object of the invention to provide an electronic musical instrument which facilitates the selection of harmony, preferably on a keyboard.
Another object is the correction of the harmony of a musical accompaniment in response to a performer who selects the harmony "behind the beat".
The applicant has discovered a unique apparatus and method for achieving these objectives. In principal apparatus aspect, the invention is used in an electronic musical instrument which controls the production of a musical accompaniment defined in part by rhythmic beats having a predetermined period. The instrument also includes harmony selection means. Means are provided for dividing the beats into first and second time segments. Additional means generate a segment of music depending on the harmony selected by the performer. During the first time segment, the means modify the accompaniment in response to a change in the selected harmony. During the second time segment, the means inhibit a change in the accompaniment due to a change in the selected harmony.
According to the principal method aspect of the invention, music signals are stored and addressed at differential rates when a harmony change occurs during the first time segment. Changes in accompaniment are inhibited when a harmony change occurs during the second time segment.
By using the foregoing techniques, the performer can change to a different harmony at the end of a beat without interrupting the continuity of the accompaniment and can hear much of the subsequent beat in the changed harmony even if the change is not completed until a portion of the subsequent beat has elapsed. Thus, harmony can be changed by an unskilled performer with a degree of accuracy and ease previously unattainable.